Growatt Inverter Client App – Java Client

Java Client for the Growatt Inverter

This Java application currently supports 3 main actions.

A1) Notify when the grid voltage is 0v (i.e. Power cut)

A2) Change power input priority (SUB / SBU)

A3) Change battery charging priority (Solar Only / Solar Priority)

A1) Notify when the grid voltage is 0v (i.e. Power cut).

Currently, the Growatt mobile app does not have any notification mechanism to alert when the grid power goes away. This app uses an ugly hack to achieve that up to some level.

The application keeps polling (once every 5 minutes) the Growatt cloud and checks if the Grid voltage is 0v. If it is, it fires a configured Gmail webhook which sends a chat message to the user. Since the Datalogger only uploads data once every 5 minutes, we can’t get an accuracy higher than 5 minites even if we change the app to run more frequently.

This will also send a power status chat every day at 7 AM to let you know that the app is running properly.

Note: Please don’t use this action unless you really need it, as this introduces considerable traffic to the Growatt cloud.

A2) Change power input priority (SUB / SBU)

This can be used to change power input priority of the inverter automatically, based on a time schedule.

This is written as a test case so that it can be automated using a Git Action workflow. Have a look at the Github workflow files in this repo.

A3) Change battery charging priority (Solar Only / Solar Priority)

This can be used to change the battery charging priority of the inverter automatically.

This is also written as a test case.

How to run?

  1. Configure authentication details in the file.
  2. To run #A1, build the repo and simply run the main method of the class.
  3. To run #A2 manually, you can use the below command.
mvn clean install -P change-settings -Dtest="MonitorTest#testOutputChangeToSUB"


mvn clean install -P change-settings -Dtest="MonitorTest#testOutputChangeToSBU"

To automate #A2, create a private git clone of this repo (as you’re configuring your credentials in step 1). Change cron jobs based on your requirement.

  1. To run #A3 manually, you can use the below command.
mvn clean install -P change-settings -Dtest="MonitorTest#testChargingChangeToSolarOnly"


mvn clean install -P change-settings -Dtest="MonitorTest#testChargingChangeToSolarPriority"


Special Thanks to bhathiya/growatt-inverter-client

Sako Isun Inverter USB Driver + Monitoring

This is an Solar inverter monitoring and controlling system for hybrid inverters, Following are the main components in the system.

  • Solar Inverter driver program to communicate with USB serial port (Python)
  • Python Flask based REST API to expose the data
  • ReactJS based web portal (PWA) for monitoring and controlling the inverter

Tested Solar inverters

Currently we have tested this on Sako Isun 3KW.

Supported compute devices

  • Raspberry pi
  • Orange pi
  • Any Unix device

Hardware setup

  • Use the USB cable provided with the inverter or any appropriate USB cable
  • Connect the USB cable to any of the supported device
  • Install the pre-requisite mentioned in the following install steps
  • Run the tools/ script to connection between inverter and the compute device
  • For any issues check the Troubleshoot section

How it works

Most of the Hybrid(Chinees) inverters comes with the following Serial interface

Bus 001 Device 002: ID 0665:5161 Cypress Semiconductor USB to Serial

For this VendorID and ProductID there are several UPS and inverter devices using this serial com device. But this device had no drivers for Raspberry pi, So when the inverter is connected to a Raspberry pi(or similar) compute device , it detects as a USB block storage device


not as a USB serial communication device.


/dev/ttyS0 or /dev/USB0

To establish communication between the inverter and the compute device we had to use pyUSB approach described in here. For the basic working principles of Inverter – Compute device (Raspberry pi) communication check the above article.

Another important piece of the puzzle was to find out the communication protocol. This document from a random generous Czech inverter site.

Without this, Decoding the values sent from inverter was a challenge

and the meanings of

  • QPIGS: Device general status parameters inquiry


  • QMOD: Device Mode inquiry

were like greek!

Once the communication is established it’s was just a matter of routing the data to client application (React app) to present the data.

We use Flask to implement REST API and ReactJS, MUI , React Query in the UIs.


Most of the Raspberry pi & Orange Pi variations doesn’t come with pip pre-installed, Hence we have to run this

  • sudo apt-get install python3-pip

Install the Python USB communication library

  • python3 -m pip install pyusb

This is required for the following crc16 library

  • sudo apt-get install python3-dev

CRC16 is used to generate the 2 byte CRC, CRC is a way of detecting accidental changes in data storage or transmission

| Note: This only works upto python 3.9 versions, If you have a latest version of Python 3.10+, This will not work

  • python3 -m pip install crc16

Add a Udev rule as shown below, This is required to allow communicating with the USB device for none-sudoers users. Example file is given in


in this repo

  • sudo vim /etc/udev/rules.d/99-.rules

Restart the Udev admin to apply the changes

  • sudo udevadm control –reload-rules && sudo udevadm trigger

Accessing from anyway

Currently this only support monitoring through the local network, If you want to monitor or control the device through internet, Then you need to expose the APIs through Choreo (It’s free) like API proxy service or Buy a Blynk subscription and publish data to blynk.


  • Use
sudo lsusb

to check whether the Serial Communication device has been detected by the operating system if so it show show as

Bus 001 Device 002: ID 0665:5161 Cypress Semiconductor USB to Serial

in the output of lsusb command

Special Thanks To (tmkasun/solar-hybrid-inverter-monitor)

Difference Between MPPT and PWM Charge Controller


MPPT Solar Charge Controller

PWM Solar Charge Controller

1. What they do

The PWM controller is in essence a switch that connects a solar array to a battery. The result is that the voltage of the array will be pulled down to near that of the battery.

The MPPT controller is more sophisticated (and more expensive): it will adjust its input voltage to harvest the maximum power from the solar array and then transform this power to supply the varying voltage requirement, of the battery plus load. Thus, it essentially decouples the array and battery voltages so that there can be, for example, a 12 volt battery on one side of the MPPT charge controller and a large number of cells wired in series to produce 36 volts on the other.

As array size increases, cable length will increase. The option to wire more panels in series and thereby decrease the cable cross sectional area with a resultant drop in cost, is a compelling reason to install an MPPT controller as soon as the array power exceeds a few hundred Watts (12 V battery), or several 100s of Watts (24 V or 48 V battery).


The PWM charge controller is a good low cost solution for small systems only, when solar cell temperature is moderate to high (between 45°C and 75°C).


To fully exploit the potential of the MPPT controller, the array voltage should be substantially higher than the battery voltage. The MPPT controller is the solution of choice for higher power systems (because of the lowest overall system cost due to smaller cable cross sectional areas). The MPPT controller will also harvest substantially more power when the solar cell temperature is low (below 45°C), or very high (above 75°C), or when irradiance is very low.

  • Charging Method
    The difference between the PWM controller and the MPPT solar controller is that they charge differently. The PWM is charged in a three-stage charging mode. MPPT is the maximum power tracking technology, and the charging efficiency can be increased to about 30%.
  • Voltage
    When the MPPT solar controller is used, the charging efficiency is more obvious when the high-voltage solar panel is used to charge the low-voltage battery. If the voltage of the solar energy and the battery are the same, for example, it is 12V, then the difference between the practical PWM and the MPPT controller is not very big.
  • Power
    If the power of the solar panel is small, it is more appropriate to select a PWM controller. Relatively speaking, if the power of the solar panel is large, MPPT is selected.Solar controllers, because the cost of MPPT solar controllers is high, if your solar panel power is small, it is a waste of MPPT controller.